class Shape {
    public void draw() {
        System.out.println("画图形！");
    }
}

class Rect extends Shape {
    @Override
    public void draw() {
        System.out.println("画一个矩形！");
    }
}

class Cycle extends Shape {
    @Override
    public void draw() {
        System.out.println("画一个圆形");
    }
}

class Triangle extends Shape {
    @Override
    public void draw() {
        System.out.println("画一个三角形！");
    }
}

public class Demo4_5 {
    //使用多态
    public static void drawMap(Shape shape) {
        shape.draw();
    }

    public static void main(String[] args) {
        drawMap(new Cycle());
        drawMap(new Rect());
        drawMap(new Triangle());
    }
}
